Sheet-feeding auxiliary device, image forming device, and image reading device

ABSTRACT

A sheet-feeding auxiliary device includes a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path, a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member, and a driving unit that drives the rotating member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present document incorporates by reference the entire contents of Japanese priority document, 2005-256594 filed in Japan on Sep. 5, 2005, 2005-270084 filed in Japan on Sep. 16, 2005, 2005-312815 filed in Japan on Oct. 27, 2005, 2006-109911 filed in Japan on Apr. 12, 2006, 2006-151622 filed in Japan on May 31, 2006 and 2006-173768 filed in Japan on Jun. 23, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet-feeding auxiliary device, an image forming device, and an image reading device used in an image forming apparatus such as a printer, a copier, or a facsimile machine, or an image recording apparatus such as a scanner.

2. Description of the Related Art

It has been desired to develop an image forming device capable of dealing with sheets each having a different thickness in a compact body. For paper feed, when a sheet of paper is fed from a paper cassette to a predefined position of the image forming unit without changing the feed direction, a sheet path stretches horizontally, so that a size of the image forming device inevitably becomes larger in horizontal direction and occupies a large area.

Japanese Patent Application Laid-Open No. H10-265070 and Japanese Patent Application Laid-Open No. 2002-274702 disclose a technique in which a feed direction is changed right after a sheet is fed from the paper cassette by curving the sheet with a circular guiding surface. For example, a sheet stored in the horizontal paper cassette is fed and curved straight upward to change the feed direction. Examples of the technique are explained in FIGS. 20, 21, 22A, 22B, 22C, and 22D. In the example shown in FIG. 20, a pick-up roller 51 feeds a top sheet out of a pile of sheets “P” stored in a paper cartridge. A feed roller 52 and a reverse roller 53 separate the top sheet from the others. This type of sheet-separating process is called FRR. After passing through the separating section (i.e., the feed roller 52 and the reverse roller 53), the sheet in a path is led by a sheet guiding member 17 and an inside guiding member 50 by which a feed direction thereof is turned straight upward, and goes upward to an intermediate transferring section or other sections located downstream led by a pair of grip rollers 55 a and 55 b. In the configuration, right after the sheet passes through the separating section, the feed direction of the sheet is changed and the sheet is fed and led by the pair of the grip rollers, so that a distance between the separating section and the pair of grip rollers can be short. As a result, the technique enables reduction in both size and cost of an image forming device. However, as shown in FIGS. 21, 22A, 22B, 22C, and 22D, the sheet gains, right after the sheet passes through the separating section, a feed load from the sheet guiding member 17 sliding thereon (see FIG. 21). Next, the sheet gains another feed load from the sheet guiding member 17 and the inside guiding member 50, sliding thereon (see FIGS. 22A, 22B, 22C, and 22D). In particular, when a firm and thick sheet is fed, the feed load increases remarkably. In the FRR, it is hard to strengthen a feed power from the feed roller 52 received by a sheet, because as the feed power becomes larger, a load received by the reverse roller 53 also becomes larger. The larger feed power hinders the performance for separation and causes an excessive driving torque and roller wear, so that it is difficult to strengthen the feed power. Therefore, when a firm sheet like thick paper, a postcard, or an envelope is fed, the problem such as a feed delay or miss-feeding may occur due to the large feed load. Like in the FRR, although another separating technique is employed in the image forming device, feeding of, especially, a firm sheet like thick paper may delay or fail due to the feed load on the sheet guiding member 17 and the inside guiding member 50 where the feed direction is changed.

There is a technique to solve the problem by employing a configuration in which a horizontal feed portion is provided right after the separating section where the sheet is fed straight forward without turning the feed direction and an additional pair of carriage rollers (a pair of grip rollers) is positioned. The feed direction is changed after the additional pair of carriage rollers holds the sheet, in other words the feed direction is changed downstream of the additional pair of carriage rollers.

The technique described above requires the horizontal feed portion provided right after the separating section, which makes the image forming device larger in horizontal direction. Furthermore, the cost will increase due to additional rollers (i.e., the additional pair of carriage rollers). As a result, the advantages in size and cost of paper feed technique employing the configuration in which a feed direction is changed right after the separating section is spoiled.

There is another technique to solve the problem as shown in FIG. 23, and the technique employs a configuration in which a large roller is used as the grip driving roller 55 a, and a driven roller 17 b is additionally provided on the horizontal feed portion right after the separating section to increase the feed power while curving the sheet.

In the configuration, the grip driving roller 55 a should be large sufficient to have a curvature radius depending on the firmness of the sheet to be used. Therefore, the image forming device becomes large. Furthermore, change of a layout of other components may disadvantageously be compelled due to enlargement of the grip driving roller 55 a.

It is conceivable to employ still another configuration to solve the problem in which the inside guiding member 50 is removed. In the configuration, the sheet with upward curve may not reach a position where the grip driving roller 55 a and the driven roller 17 b nip the sheet. In addition, foreign materials from inside the image forming device like toner powders and grease may spread to reach the surface of the sheet.

The present invention has been made to solve the problems occurring in the conventional sheet feed unit in the image forming device or the like. It is an object of the present invention to provide a feed system allowing for downsizing and cost reduction, in which a sheet is fed without fail from the feed roller 52 to the carriage roller located downstream of a feed turning position, and a feed load on the paper is kept at a minimum level.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve the problems in the conventional technology.

A sheet-feeding auxiliary device according to one aspect of the present invention includes a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.

An image forming device according to another aspect of the present invention includes a sheet-feeding auxiliary device that is arranged at an inner circumferential side of a sheet path. The sheet-feeding auxiliary device includes a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.

An image reading device according to still another aspect of the present invention includes a document tray on which a sheet of a document is placed; a document feeding unit that feeds the sheet of the document into a sheet path; a reading unit that reads the sheet of the document fed in the sheet path, as an image; a reversing unit that reverses one surface and other surface of the sheet of the document fed in the sheet path; a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.

A sheet-feeding auxiliary device according to still another aspect of the present invention includes a sheet guiding means for changing a direction of feeding a sheet in a sheet path member, the sheet guiding means being provided outside of a feed turning portion; a rotating means that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving means for driving the rotating member.

The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view for explaining a general configuration of an image forming device according to a first embodiment of the present invention;

FIG. 2 is a side view for explaining a sheet path of the image forming device in FIG. 1;

FIG. 3A is an enlarged side view for explaining a portion of a sheet-feeding auxiliary device in FIG. 1 where a feed direction of a sheet fed right after from a paper cassette is changed to an upward direction;

FIG. 3B is an enlarged side view for explaining the situation in which the sheet fed from the paper cassette of the sheet-feeding auxiliary device in FIG. 3A goes forward and an area of the sheet held by rollers becomes larger;

FIG. 4 is a perspective view of a turn roller and front and rear rollers against the turn roller of the sheet-feeding auxiliary device from an axial direction according to the first embodiment;

FIG. 5 is a side view for explaining a driving system for the turn roller and a grip driving roller of the sheet-feeding auxiliary device according to the first embodiment;

FIG. 6 is a perspective view for explaining a driving system for the turn roller and a grip driving roller of the sheet-feeding auxiliary device according to the first embodiment;

FIG. 7 is a perspective view for explaining a driving system for the turn roller and a grip driving roller of the sheet-feeding auxiliary device according to a second embodiment of the present invention;

FIG. 8 is a side view for explaining a driving system of the turn roller in the sheet-feeding auxiliary device according to a second embodiment of the present invention;

FIG. 9 is a perspective view of the turn roller according to a fourth embodiment of the present invention provided with auxiliary turn rollers at both ends thereof;

FIG. 10A is an enlarged side view of a configuration of the sheet-feeding auxiliary device according to a fifth embodiment of the present invention;

FIG. 10B is an enlarged side view for explaining when a belt pulley in FIG. 10A is retracting;

FIG. 10C is a perspective view for explaining when the sheet-feeding auxiliary device in FIG. 10A is in a driving state;

FIG. 11 is a perspective view for explaining the situation in which the sheet-feeding auxiliary device according to the fifth embodiment is mounted on the image forming device;

FIG. 12A is an enlarged side view of a configuration of the sheet-feeding auxiliary device according to a sixth embodiment of the present invention;

FIG. 12B is an enlarged side view for explaining when a belt pulley in FIG. 12A is retracting;

FIG. 12C is a perspective view for explaining when the sheet-feeding auxiliary device in FIG. 12A is in a driving state;

FIG. 13 is an enlarged side view for explaining a configuration in which the belt pulley and a carriage belt are attached with a pulley shaft of the sheet-feeding auxiliary device according to the sixth embodiment;

FIG. 14 is an enlarged side view for explaining another configuration in which the belt pulley and a carriage belt are attached with a pulley shaft of the sheet-feeding auxiliary device according to the sixth embodiment;

FIG. 15 is a side view for explaining a modification of the sheet-feeding auxiliary device according to the sixth embodiment in which a roller is replaced with the pulley and the carriage belt;

FIG. 16 is a perspective view of a configuration of the carriage belt and the related pulleys of the sheet-feeding auxiliary device according to the sixth embodiment;

FIG. 17 is a perspective view for explaining the situation in which the sheet-feeding auxiliary device according to the sixth embodiment is mounted on the image forming device;

FIG. 18 is a side view for explaining an overview of a modified configuration of the image forming device according to the present invention in which an image is directly transferred onto the sheet;

FIG. 19 is a side view of an automatic document feeder;

FIG. 20 is an enlarged side view for explaining a portion of a sheet-feeding auxiliary device according to a conventional technology where a feed direction of a sheet fed right after from a paper cassette is changed to an upward direction;

FIG. 21 is an enlarged side view for explaining the situation in which, in the conventional sheet-feeding auxiliary device, a sheet fed from a paper cassette goes forward;

FIGS. 22A to 22D are schematics arranged in order of time for explaining the situation in which a firm sheet is fed through a curving path in the conventional sheet-feeding auxiliary device; and

FIG. 23 is a side view of a modified configuration of the conventional sheet-feeding auxiliary device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.

FIG. 1 is a side view for explaining a general configuration of an image forming device 100 according to a first embodiment of the present invention. The image forming device 100 includes an intermediate transfer belt 11 made up of a plurality of rollers and a belt bridged between the rollers in nearly the center thereof, and four image forming units 10M, 10C, 10Y, and 10Bk located along a downside path of the intermediate transfer belt 11.

The image forming units 10M, 10C, 10Y, and 10Bk include photoconductive drums 1M, 1C, 1Y, and 1Bk functioning as carriers of images, respectively. Surrounding the photoconductive drums 1M, 1C, 1Y, and 1Bk, charging units 2M, 2C, 2Y, and 2Bk, developing units 3M, 3C, 3Y, and 3Bk, and cleaning units 4M, 4C, 4Y, and 4Bk are provided respectively. Opposed to the photoconductive drums 1M, 1C, 1Y, and 1Bk and inside of the intermediate transfer belt 11, primary transfer rollers 12M, 12C, 12Y, and 12Bk are provided respectively. The image forming units 10M, 10C, 10Y, and 10Bk are similar to each other in the configuration, except in colors of toner powders. The toner powders of the image forming units 10M, 10C, 10Y, and 10Bk are magenta, cyan, yellow, and black, respectively. The image forming units 10M, 10C, 10Y, and 10Bk are arranged from left to right, and are removable from the body of the image forming device 100.

Below the image forming units 10M, 10C, 10Y, and 10Bk, an optical writing unit 14 is provided. The optical writing unit 14 includes a polygon mirror and a set of mirrors (not shown) which emit modulated laser beams to each of surfaces of the photoconductive drums 1M, 1C, 1Y, and 1Bk. Although the optical writing unit 14 can be provided for each of the image forming units 10M, 10C, 10Y, and 10Bk, it is recommended to share one unit of the optical writing unit 14 from a view point of cost performance. The intermediate transfer belt 11 and the optical writing unit 14 are removable from the body of the image forming device 100.

In the bottom of the image forming device 100, two paper cassettes 15 a and 15 b with paper feed units 16 a and 16 b are provided respectively. The paper feed units 16 a and 16 b have a similar configuration and employ a similar mechanism for changing a feed direction of a recording medium like a sheet of paper, “sheet” fed from the paper cassette. The feed direction of the sheet is changed upward by a pair of paper stop rollers 18. Above the pair of paper stop rollers 18, a secondary transfer roller 19 is provided opposite to a transfer opposed roller 13. Both of the pair of paper stop rollers 18 and the transfer opposed roller 13 form a secondary transfer section.

Above the secondary transfer section, a fusing unit 20 is provided, and above the fusing unit 20, a first switching claw 21, a second switching claw 22, a third switching claw 23 for switching a sheet feed direction are provided. Each of the switching claws 21 to 23 is controlled by an actuator like a solenoid (not shown). Reference numerals 24 to 27 denote pairs of carriage rollers arranged at desired positions in the sheet path. Reference numerals 35 to 41 denote sheet sensors arranged at desired positions in the sheet path.

A receiving tray 30 is provided at the top of the image forming device 100. It is provided at a diagonally upper left position from the fusing unit 20 is a pair of ejecting rollers 29 for ejecting the sheet to the receiving tray 30. A reverse path 61 and re-path 62 are formed in a duplex unit 60. A pair of first reverse rollers 31 is provided at an entrance of the reverse path 61 (in the upper side of the image forming device 100) and a pair of second reverse rollers 32 is provided in a middle of the reverse path 61. The pairs of reverse rollers 31 and 32 are rotatable in both clockwise and counterclockwise. The pair of carriage rollers 26 is positioned at one-third and the pair of carriage rollers 27 is positioned at two-thirds of the re-path 62. The third switching claw 23 is positioned next to the first pair of reverse rollers 31, in other words at an entrance of the re-path 62 from the reverse path 61.

A bypass tray 33 is provided at a side of the duplex unit 60. The bypass tray 33 is retractable. The bypass tray 33 in FIG. 1 is prepared to be used. A paper feed unit 34 is provided to feed a sheet from the bypass tray 33. The paper feed unit 34 has the same configuration as the paper feed units 16 a and 16 b. A re-feed roller 28 is provided at a side of the paper feed unit 34 located inside of the image forming device 100. A driven roller 72 is welded with pressure to an upper side of the re-feed roller 28 and a driven roller 73 is welded with pressure to a downside of the re-feed roller 28. The re-feed roller 28 is rotatable in both clockwise and counterclockwise. When the sheet is re-fed from the re-path 62, the re-feed roller 28 rotates in the counterclockwise direction, and when the sheet is fed from the bypass tray 33, the re-feed roller 28 rotates in the clockwise direction.

An image forming process by the image forming device 100 having the above configuration is described below. The photoconductive drums 1M, 1C, 1Y, and 1Bk are rotated by a driving unit (not shown) in the clockwise direction and charged with a uniform polarity by the charging units 2M, 2C, 2Y, and 2Bk on the surfaces thereof. The optical writing unit 14 emits a laser beam to the charged surfaces of the photoconductive drums 1M, 1C, 1Y, and 1Bk to form electrostatic latent images on the surfaces. The photoconductive drums 1M, 1C, 1Y, and 1Bk are exposed based on mono-color image information made by resolving full-color image information by color (magenta, cyan, yellow, and black). After forming the electrostatic latent images, each color of toner powders from the developing units 3M, 3C, 3Y, and 3Bk are attached to the surfaces to visualize as toner images.

As the intermediate transfer belt 11 moves in the counterclockwise direction (see an arrow), the toner images on each of the photoconductive drums 1M, 1C, 1Y, and 1Bk are sequentially transferred onto the intermediate transfer belt 11 at each of the image forming units 10M, 10C, 10Y, and 10Bk with the primary transfer rollers 12M, 12C, 12Y, and 12Bk. As a result, the full-color toner image is carried on the surface of the intermediate transfer belt 11.

The image forming device 100 can print a mono-color, bicolor, or tricolor image by using one, two, or three of the image forming units. The image forming unit 10Bk (on the extreme right) works alone for mono-color printing. After the toner images are transferred to the intermediate transfer belt 11, the cleaning units 4M, 4C, 4Y, and 4Bk remove the toner powders remained on the surface of the photoconductive drums 1M, 1C, 1Y, and 1Bk, and the photoconductive drums 1M, 1C, 1Y, and 1Bk are discharged by neutralization units (not shown) on the surface for the subsequent image-forming process.

The sheet is -selectively fed from the paper cassette 15 a, 15 b, or the bypass tray 33 and sent by the pair of paper stop rollers 18 to the secondary transfer position at a suitable timing matching with the toner images carried on the intermediate transfer belt 11. The secondary transfer roller 19 is charged with a polarity opposite to that on the toner image on the surface of the intermediate transfer belt 11, so that the toner image is transferred to the sheet at a time. The toner image on the sheet is fused and fixed with thermal and pressure as passing through the fusing unit 20. The sheet with the fixed image is ejected by the pair of ejecting rollers 29 to the receiving tray 30 on the top of the image forming device 100.

The sheet path is described in details below. FIG. 2 is a side view for explaining the sheet path of the image forming device in FIG. 1. A solid line (1) denotes a sheet path for single-side printing when the sheet is fed from the paper cassette 15 a or 15 b.

An optional receiving tray such as a 4-bin tray for sorting (not shown) can be attached to the upper side of the image forming device, in other words above the second switching claw 22, and the sheet can be ejected onto the optional receiving tray. A dotted line (2) denotes a sheet path for ejecting the sheet after passing through the fusing unit 20 onto the optional receiving tray.

When duplex printing is performed, a sheet with a fixed toner image on one side thereof is fed into the reverse path 61 by suitably switching the first to third switching claws 21, 22, and 23. Next, the first and second pairs of reverse rollers 31 and 32 are rotated in the clockwise direction (“forward direction” in FIG. 1). A dashed-two dotted line (3) denotes a sheet path after the sheet passes through the pair of carriage roller 25 to enter into the reverse path 61.

After the sheet sensor 40 detects the back end of the sheet in the reverse path 61, the first and second pairs of reverse rollers 31 and 32 are rotated in the counterclockwise direction (“backward direction” in FIG. 1) to reverse the sheet back. The reversed sheet is sent into the re-path 62 by suitably switching the third switching claw 23.

The re-path 62 joins at the bottom thereof with the sheet path stretching from the bypass tray 33, and also joins at an inner position from the re-feed roller 28 with the sheet path stretching from the paper cassettes 15 a and 15 b. In the re-path 62, the sheet is fed by the pairs of carriage roller 26 and 27, and then by the re-feed roller 28 to the pair of paper stop rollers 18. A dashed line (4) denotes a sheet path after the sheet passes through the third switching claw 23 in the re-path 62. A dotted line (5) denotes a sheet path from the bypass tray 33 to a position over the re-feed roller 28 when the sheet is fed from the bypass tray 33.

When duplex printing is processed, the sheet is reversed by passing through the re-path 62 after going backward through the reverse path 61, the toner image is transferred from the intermediate transfer belt 11 onto the back side of the sheet, the toner image on the back side of the sheet is fixed by the fusing unit 20, and the sheet with the fixed image is ejected onto the receiving tray 30 or the optional tray (not shown).

The sheet-feeding auxiliary device according to the first embodiment of the present invention is described in details below. FIG. 3A is an enlarged side view for explaining a portion of the sheet-feeding auxiliary device in FIG. 1 in which a feed direction of the sheet fed right after from the paper cassette is changed upward, namely “a feed turning portion”. The paper cassettes 15 a and 15 b have an identical configuration and also the portions, in the feed turning portion, of changing the feed direction for the paper cassettes 15 a and 15 b are also identical, so that description for the upper paper cassette 15 a is made only. The overlapped description for the lower paper cassette 15 b is omitted below.

A top sheet P out of a pile of paper sheets stored in the paper cassette 15 a is fed by the pick-up roller 51, and separated from other sheets by the feed roller 52 and the reverse roller 53 in FRR process. According to the first embodiment, a turn roller 54 is provided inside of the sheet path positioned oppose to the sheet guiding member 17. The turn roller 54 is rotated by a driving system described below. An outer circumferential surface of the turn roller 54 is formed from materials with a high coefficient of friction such as ethylene-propylene rubber or urethane rubber. Namely, the feed roller 52 and the reverse roller 53 are positioned upstream of the turn roller 54 in the sheet path, and a pair of grip rollers 55, composed of a grip driving roller 55 a and a grip driven roller 55 b, is positioned downstream of the turn roller 54.

In the feed turning portion, after the top sheet P is fed by the pick-up roller 51, the feed direction of the sheet is gradually turned upward from the horizontal direction, as the sheet is sliding on the sheet guiding member 17. When an edge of the sheet is fed at a predefined position, the top face of the sheet contacts the turn roller 54. At the predefined position, the edge of the sheet hits against an upper surface 17 a of the sheet guiding member 17, bends upward due to the elasticity thereof, and is pressed by the turn roller 54 in the direction indicated by an arrow in FIG. 3A. Because the turn roller 54 rotates with a driving force and is made from the material with the high coefficient of friction in the outer circumferential surface thereof, the sheet is moved by the turn roller 54 in the upper right direction (see the arrow) As the sheet goes forward with the angle turning higher, an area of the sheet located downstream of the turn roller 54 becomes larger and the sheet receives a larger power, so that a length of the sheet wound around the turn roller 54 becomes longer. FIG. 3B is an enlarged side view for explaining the situation in the sheet fed from the paper cassette of the sheet-feeding auxiliary device goes forward and an area of the sheet contacting on the rollers becomes larger. The identical members are denoted with the same reference numerals and descriptions of the identical members are omitted. As described above, the sheet passing through the feed turning portion can remove the feed load to obtain the power to go forward from the turn roller 54, so that the sheet is fed forward without fail changing the feed direction upward. Next, the sheet is held by the grip driving roller 55 a and the grip driven roller 55 b and fed upward in the vertical direction with a torque from the pair of grip rollers 55 a and 55 b.

The sheet guiding member 17 has the upper surface 17 a positioned opposite to the turn roller 54 to turn the feed direction. Working together with the turn roller 54, the sheet guiding member 17 can smoothly turn the feed direction.

Although the feed direction is changed right after the sheet passes through the feed roller 52 and reverse roller 53, the turn roller 54 located between a set of the feed roller 52 and the reverse roller 53 and the pair of grip rollers 55 makes a distance longer between the set of the feed roller 52 and the reverse roller 53 and the pair of grip rollers 55, without providing a portion where the sheet goes horizontally, “horizontal feed portion”. Also, the configuration requires a few additional members. Therefore, the image forming device can be downsized and prevent cost increase.

Because the outer circumferential surface of the turn roller 54 is made from a material with a high -coefficient of friction, the power from the turn roller 54 is delivered without fail to the sheet, which ensures reduction of the load on the sheet at the feed turning portion. The turn roller 54 can deliver the power to various types of sheets. To describe the configuration centering on the turn roller 54, the feed roller 52 is a front roller and the grip driving roller 55 a and the grip driven roller 55 b are rear rollers against the turn roller 54.

FIG. 4 is a perspective view of the turn roller 54 and front and rear rollers against the turn roller 54 of the sheet-feeding auxiliary device according to the first embodiment viewed in the axial direction. The identical members are denoted with the same reference numerals, and the descriptions of the identical members are omitted. The turn roller 54 is configured of a left roller 54L and a right roller 54R. The feed roller 52 is positioned between the left roller 54L and the right roller 54R. The grip driving roller 55 a is configured of three rollers; a roller 55 a-L, a roller 55 a-C, and a roller 55 a-R. The left roller 54L of the turn roller is positioned between the rollers 55 a-L and 55 a-C, and the right roller 54R of the turn roller is positioned between the rollers 55 a-C and 55 a-R. Because of the configuration, when the rollers are depicted from the shaft direction like in FIG. 3A and FIG. 3B, parts of the feed roller 52 and the turn roller 54 are overlapped. Similarly, parts of the turn roller 54 and the grip driving roller 55 a are overlapped. In FIG. 4, the left side is located close to a surface of the image forming device 100, and the right side is located inside of the image forming device 100.

By suitably arranging the turn roller 54 and the front and rear rollers so that the rollers are overlapped on each other when viewed from the side, a space occupied by the turn roller 54 and the front and rear rollers becomes small. As a result, the feed turning portion is enabled to reduce the load with occupying a small space. Also a configuration is effective for space-saving in which the turn roller 54 and either one of the front and rear rollers are overlapped on each other.

In the turn roller 54, a distance between the outer surface of the left roller 54L and the outer surface of the right roller 54R is about 90 millimeters. The distance of 90 millimeters is suitable for a firm sheet generally used in the image forming device like a printer, for example a postcard (100 millimeters in width), an envelope (in general use, 92 millimeters or wider in width), to be fed. The turn roller 54 is positioned at a position corresponding to a central arrangement of the sheet employed in the image forming device 100.

FIGS. 5 and 6 are a side view and a perspective view for explaining a driving system for the turn roller 54 and the grip driving roller 55 a of the sheet-feeding auxiliary device according to the first embodiment. The identical members are denoted with the same reference numerals and the descriptions of the identical members are omitted. A gear 54 g is attached to a shaft 54 c of the turn roller 54 having the left roller 54L and the right roller 54R attached thereto. A gear 55 g is attached to a shaft 55 d of the grip driving roller 55 a having the rollers 55 a-L, 55 a-C, and 55 a-R attached thereto. An idler gear 56 (not shown in FIG. 6) engaging with the gears 54 g and 55 g is provided. When a driving unit (not shown) rotates the shaft 55 d of the grip driving roller 55 a, the turn roller 54 is rotated via the idler gear 56. Therefore, the turn roller 54 rotates in synchronism to the grip driving roller 55 a, in other words the turn roller 54 rotates in synchronism to the rear rollers with an easy operation. As a result, a linear speed of the turn roller 54 is set substantially equal to that of a sheet linear speed.

Because the linear speed of the turn roller 54 is set substantially equal to that of the sheet linear speed, the sheet does not receive damages from, for example, abrasion. When the sheet, after fed from the paper cassette 15 a or 15 b, is held to be fed by the front rollers (the feed roller 52 and the reverse roller 53) and the rear rollers (the pair of grip roller 55), with the turn roller 54 rotating at a speed different from the sheet linear speed, the sheet may be damaged from, for example, abrasion. When the outer circumferential surface of the turn roller 54 is made from the member with a high coefficient of friction, the sheet receives large damage.

Generally, the paper stop roller and a carriage roller located upstream of the paper stop roller are rotated in synchronism to each other. The first embodiment has the similar configuration. When the pair of paper stop rollers 18 stops the sheet to match the timing, the long sheet can be held by the pair of grip rollers 55 at the end thereof. Therefore, when the pair of paper stop rollers 18 stops the sheet, the pair of grip rollers 55 should be stopped. In some cases, the end of the sheet can remain at the turn roller 54 over the pair of grip rollers 55. As a result, when the pair of grip rollers 55 stops to stop the sheet feed with the turn roller 54 rotating, the sheet can receive damage from, for example, abrasion. When the outer circumferential surface of the turn roller 54 is made from the member with a high coefficient of friction, the sheet receives large damage.

However, according to the first embodiment, the turn roller 54 rotates and stops in synchronism to the grip driving roller 55 a, so that the turn roller 54 does not cause the turn roller 54 to be damaged from, for example, abrasion. Besides, the simple configuration enables to keep the cost increase at a low level. As the driving system for the turn roller 54, a driving system composed of a pulley and a belt can be used instead of the driving system with gears.

The grip driving roller 55 a is, like in the general image forming device, supported at the shaft 55 d by front and rear housings (not shown), and is driven by the driving system (not shown) provided inside of the image forming device 100. As can be seen from FIG. 6, the shaft 54 c of the turn roller 54 is such short, i.e. a little longer than the distance of 90 millimeters between the left roller 54L and the right roller 54R, with each of the edges projecting a little from the left roller 54L or the right roller 54R, that is supported by members like a frame (not shown) with shaft bearings 57. The force to drive the turn roller 54 is delivered via a series of the gears 54 g and 55 g (or a pulley and a belt) from the shaft 55 d of the grip driving roller 55 a. Therefore, to support and drive the turn roller 54, the long shaft is not required that stretches between the front and rear housings of the image forming device 100. As a result, the configuration contributes low-space and low-cost.

As described above, the sheet-feeding auxiliary device of the image forming device 100 includes the feed roller 52, the turn roller 54 made from the material with a high coefficient of friction on the surface thereof positioned right after the reverse roller 53, the upper surface 17 a of the sheet guiding member 17 for turning the feed direction of the sheet, each located in the path, in which the turn roller 54 is driven in conjunction with the pair of grip rollers 55 arranged with the rotating directions reverse to each other. This configuration ensures sheet feed without fail in a small space and minimizes damages on the sheet.

A sheet-feeding auxiliary device of an image forming device 100 according to a second embodiment of the present invention is described in details bellow. The image forming device 100 is similar to that according to the first embodiment. Therefore, the identical components are denoted with the same reference numerals and the descriptions of the components are omitted. The sheet-feeding auxiliary device is similar to that according to the first embodiment excepting that a rotatable auxiliary turn rollers 58 are additionally provided at a position coaxial to the turn roller 54, and that the driving system for the turn roller 54 has a different configuration. The overlapped descriptions are omitted and only different portions are described below.

FIG. 7 is a perspective view of a driving system for the turn roller 54 and the grip driving roller 55 a according to the second embodiment. The identical members are denoted with the same reference numerals, and the descriptions of the members are omitted. One auxiliary turn roller 58 is coaxially located at an outer position of the left roller 54L of the turn roller 54, and another auxiliary turn roller 58 is coaxially located at an outer position of the right roller 54R. The left roller 54L and the right roller 54R of the turn roller 54 are identical to those in FIGS. 3 to 6. The auxiliary turn roller 58 includes a rotating shaft 58 b supported by the shaft bearings 57 and a roller 58 a fixed to the rotating shaft 58 b. The roller 58 a, the left roller 54L, and the right roller 54R are identical. The shaft bearing 57 is also provided at the other end of the rotating shaft 58 b (not shown). Both of the shaft bearings 57 rotatably support the rotating shaft 58 b. The rotating shaft 58 b is coaxial to the shaft 54 c of the turn roller 54, so that the roller 58 a of the auxiliary turn roller 58 and the left roller 54L and the right roller 54R of the turn roller 54 are arranged coaxially. The roller 58 a is cylindrical with a diameter equal to that of the left roller 54L and the right roller 54R.

In the configuration shown in FIG. 7, only one roller 58 a is provided at each of the auxiliary turn rollers 58. A plurality of rollers 58 a can be provided at one of the auxiliary turn rollers 58. Although the left roller 54L and the right roller 54R of the turn roller 54 are rotated by the driving system described above, the auxiliary turn rollers 58 are rotatable but not connected to a driving system. While the sheet is being fed through the feed turning portion, the auxiliary turn rollers 58 rotate in association with forward movement of the sheet.

The auxiliary turn rollers 58 located at outer positions from both ends of the turn roller 54 allow a wide sheet to be fed without fail by contacting the sheet to help changing of the feed direction. The sheet feed operation at the feed turning portion is more stable and the feed load on the sheet can be reduced.

Besides, the configuration is simple, because the turn roller 54 in the center is driven by the driving system but the auxiliary turn roller 58 at the ends is free from the driving system. When the driving rollers extend over the full width of the sheet to be fed, the driving shaft should stretches over the width of the sheet. However, according to the second embodiment, the driving rollers (i.e. the turn roller 54) are located only in the center, so that the driving shaft is required only to stretch over the center portion of the sheet width.

FIG. 8 is a side view for explaining the driving system of the turn roller in the sheet-feeding auxiliary device according to the second embodiment. The identical members are denoted with the same reference numerals, and the descriptions of the members are omitted. An idler gear 59 is provided to engage with the gear 54 g attached to the shaft 54 c of the turn roller 54 and the gear 52 g attached to a shaft 52 c of the feed roller 52. According to the second embodiment, the turn roller 54 is driven via the idler gear 59 delivering a torque from the shaft 52 c of the feed roller 52 driven by the driving unit (not shown).

In the sheet-feeding auxiliary device according to the first embodiment, the turn roller 54 is driven in conjunction with the grip roller 55 located downstream, while, according to the second embodiment, the turn roller 54 is driven in conjunction with the feed roller 52 located upstream. The grip roller 55 is driven, like according to the first embodiment, by the driving unit (not shown) at the shaft 55 d of the grip driving roller 55 a.

In the turn roller 54, a one-way clutch (not shown) is provided between the gear 54 g and the shaft 54 c to deliver a driving force for turning the gear 54 g in the counterclockwise direction or to receive a driving force from the outside and turn the turn roller 54 from outside.

As a result, when the grip roller 55 pulls the sheet, for example, when the linear speed of the grip roller 55 is faster than that of the turn roller 54 or when the feed roller 52 stops (therefore, the turn roller 54 also stops) but the grip roller 55 rotates, the turn roller 54 can be rotated while the sheet is being fed.

As the driving system for the turn roller 54, a driving system composed of a pulley and a belt can be used instead of the driving system with gears. In this case, the identical configuration is realized by providing the one-way clutch between the pulley and the shaft 54 c of the turn roller 54.

As described above, the sheet-feeding auxiliary device of the image forming device 100 according to the second embodiment is provided with the auxiliary turn roller 58 located coaxial to the turn roller 54 and has the mechanism in which the turn roller 54 is driven in conjunction with the feed roller 52 located upstream in the sheet path. This configuration ensures sheet feed without fail in a small space and minimizes damages on the sheet.

A sheet-feeding auxiliary device of an image forming device 100 according to a third embodiment of the present invention is described in details bellow. The image forming device 100 is similar to that according to the first embodiment. Therefore, the identical components are denoted with the same reference numerals and the descriptions of the components are omitted. The sheet-feeding auxiliary device is similar to that according to the first embodiment excepting that a linear speed of the turn roller 54 can be switched. The overlapped descriptions are omitted and only different portions are described below.

A linear speed switching function is added to the turn roller 54 having the configuration identical to that shown in FIG. 7. To realize this system, the turn roller 54 is driven by, for example, a motor instead of the mechanism of delivering a driving force via the series of gears or the pulley and belt from the grip driving roller 55 a.

Until the pair of grip rollers 55 located downstream of the turn roller 54 holds the sheet, the linear speed of the turn roller 54 is set faster than that of the sheet. When the pair of grip rollers 55 holds the sheet, the turn roller 43 is switched to the speed identical to that of the sheet. As a result, the sheet is fed without fail and the possibility of damages on the sheet decreases.

When there is no roller provided at a position opposite to the turn roller 54 (i.e., the sheet is not hold by a pair of rollers), the turn roller 54 presses and feeds the sheet, but the sheet moves depending on the firmness thereof, so that slipping easily occurs. However, because the linear speed of the turn roller 54 is faster than that of the sheet until the sheet is held by the pair of grip rollers 55, the sheet can be fed without fail. Also, because the linear speed of the turn roller 54 is switched and set identical to that of the sheet when the end of the sheet is held by the pair of grip rollers 55, the possibility of damages on the sheet decreases.

Like according to the second embodiment shown in FIG. 7, the auxiliary turn rollers 58 can be added on both ends of the turn roller 54. By adding the auxiliary turn rollers 58, sheet feed becomes stable at the sheet turning portion and the load on the sheet decrease even when the sheet is wide, without employing a complicated configuration.

As described above, in the sheet-feeding auxiliary device of the image forming device 100 according to the third embodiment, the linear speed of the turn roller 54 is set faster than that of the sheet until the sheet is held by the pair of grip rollers 55, and when the sheet is held by the pair of grip rollers 55 the linear speed of the turn roller 54 is switched to a linear speed identical to that of the sheet. This configuration ensures sheet feed without fail in a small space and minimizes the damage on the sheet.

A sheet-feeding auxiliary device of an image forming device 100 according to a fourth embodiment of the present invention is described in details bellow. The image forming device 100 is similar to that according to the first embodiment. Therefore, the identical components are denoted with the same reference numerals and the descriptions of the components are omitted. The sheet-feeding auxiliary device is similar to that according to the first embodiment excepting that a surface of the turn roller 54 is made from a different material and that the linear speed of the turn roller 54 is faster than that of the sheet. The overlapped descriptions are omitted and only different portions are described below.

The left roller 54L and the right roller 54R of the turn roller 54 are made from a soft material such as sponge or foamed polyurethane. It is allowable that the left roller 54L and the right roller 54R are made, only on the outermost layer, from the soft material. The linear speed of the turn roller 54 is faster than that of the sheet. Practically, by replacing the gear 54 g of the turn roller 54 and the idler gears 56 and 59 shown in FIGS. 5 and 8 according to the first and second embodiments with those having a different number of teeth, the linear speed of the turn roller 54 can be made faster than that of the sheet. When a pulley, a belt and the like are used instead of the gears, the pulley is replaced with that having a different diameter. It is acceptable to drive the turn roller 54 with another motor.

Because the turn roller 54 is made from the soft material, when the sheet is fed and held by the pair of front rollers (i.e., the feed roller 52 and the reverse roller 53) and the pair of rear rollers (i.e., the pair of grip rollers 55) at the linear speed of the turn roller 54 faster than that of the sheet, the turn roller 54 is deformed, so that the sheet is fed through the feed turning portion without receiving the load.

When there is no roller provided at a position opposite to the turn roller 54 (i.e., the sheet is not hold by a pair of rollers), the turn roller 54 presses and feeds the sheet, but the sheet moves depending on the firmness thereof, so that slipping easily occurs. However, because the linear speed of the turn roller 54 is faster than that of the sheet, the sheet can be fed without fail.

Like according to the second embodiment, the auxiliary turn rollers 58 can be added on both ends of the turn roller 54. By adding the auxiliary turn rollers 58, sheet feed becomes stable at the sheet turning portion and the load on the sheet decreases even when the sheet is wide, without employing a complicated configuration. In this case, it is preferable to use, as the roller 58 a of the auxiliary turn roller 58, a roller identical to the left roller 54L and the right roller 54R of the turn roller 54.

FIG. 9 is a perspective view of the turn roller 54 according to a fourth embodiment of the present invention provided with auxiliary turn rollers at both ends thereof. The identical members are denoted with the same reference numerals and descriptions of identical members are omitted. The auxiliary turn rollers 58 are rotatably located on both ends of the turn roller 54. The auxiliary turn roller 58 is similar to that according to the second embodiment, and includes the rotating shaft 58 b supported by the shaft bearings 57 and the roller 58 a fixed to the rotating shaft 58 b. The roller 58 a, the left roller 54L, and the right roller 54R are identical to those according to the second embodiment. The shaft bearing 57 is also provided at the other end of the rotating shaft 58 b (not shown). Both of the shaft bearings 57 support the rotating shaft 58 b to be set rotatable. The rotating shaft 58 b is coaxial to the shaft 54 c of the turn roller 54, so that the roller 58 a of the auxiliary turn roller 58 and the left roller 54L and the right roller 54R of the turn roller 54 are arranged coaxially. The roller 58 a is cylindrical with a diameter equal to that of the left roller 54L and the right roller 54R.

In the configuration shown in FIG. 9, only one roller 58 a is provided at each of the auxiliary turn rollers 58. A plurality of rollers 58 a can be provided at one of the auxiliary turn rollers 58. As described according to the first embodiment, the turn roller 54 is rotated by the driving force delivered from the grip driving roller 55 a (i.e., the driving force is delivered via the gear 55 g, the idler gear 56, and the gear 54 g in FIG. 5, those gears arranged in order of force delivery). The auxiliary turn rollers 58 are rotatable but not driven by a driving system. While the sheet is being fed through the feed turning portion, the auxiliary turn rollers 58 rotate in association with forward movement of the sheet.

Other portions of the configuration are similar to those according to the first embodiment shown in FIGS. 3 to 6, excluding the auxiliary turn rollers 58 located on both ends of the turn roller 54. The overlapped descriptions are omitted. By providing the auxiliary turn rollers 58 on both ends of the turn roller 54, the sheet is tightly supported by the auxiliary turn rollers 58 contacting thereon even when the sheet is wide. This configuration ensures more stable sheet feed and reduces the damages on the sheet.

As described above, in the sheet-feeding auxiliary device of the image forming device 100 according to the fourth embodiment, the turn roller 54 is made from the soft material such as sponge or foamed polyurethane, and the number of driving gears at the turn roller 54 is larger than that at the pair of grip rollers 55. Because the turn roller 54 is deformable, when the turn roller 54 rotates faster than the sheet feed, the sheet is fed without fail in a small space and damage on the sheet is minimized.

Although the first to the fourth embodiments have been described with reference to the related drawings, the present invention is not limited to the embodiments. For example, when the auxiliary turn roller 58 is provided adjacent to the turn roller 54, it is allowable to provide the auxiliary turn roller 58 on one of ends of the turn roller 54 instead of both ends. More practically, when the sheet is placed along one side, the configuration is allowable in which the turn roller 54 is located close to the side and the auxiliary turn roller 58 is provided at the end (opposite to the side) of the turn roller 54.

It is acceptable to modify in the number and a diameter of rollers at the turn roller 54 or employ another driving system for the turn roller 54. The materials for the turn roller 54 described above are exemplary and another material can be used if required. Furthermore, another separating process can also be employed for. the separating section other than the FRR.

A sheet-feeding auxiliary device of an image forming device 100 according to a fifth embodiment of the present invention is described in details bellow. The image forming device 100 is similar to that according to the first embodiment. Therefore, the identical components are denoted with the same reference numerals and the descriptions of the components are omitted. The sheet-feeding auxiliary device is similar to that according to the first embodiment excepting that a sheet feed auxiliary section including two pulleys and a carriage belt is provided at a position opposite to the grip driven roller 55 b of the sheet-feeding auxiliary device. The overlapped descriptions are omitted and only different portions are described below.

The sheet-feeding auxiliary device according to the fifth embodiment is described in detail with reference to FIGS. 10A and 10B. FIG. 10A is an enlarged side view of a configuration of the sheet-feeding auxiliary device. The identical members are denoted with the same reference numerals and descriptions of identical members are omitted. A first belt pulley 63 functioning as a first carriage roller in a vertical feed portion, a second belt pulley 64 fixed to an idler shaft, and a carriage belt 65 bridged between the first and second belt pulleys 63 and 64 are located at one side of a curve where the FRR sheet feed mechanism including the pick-up roller 51, the feed roller 52, and the reverse roller 53 and the vertical feed portion is joined. The carriage belt 65 is made of a conductive material which is protected from static electricity that may occur due to friction on the sheet.

FIG. 10B is an enlarged side view for explaining when the belt pulley of the sheet-feeding auxiliary device. The identical members are denoted with the same reference numerals and the descriptions of the identical members are omitted. FIG. 10C is a perspective view for explaining the situation in which the sheet-feeding auxiliary device is in a driving state. The grip driven roller 55 b positioned at the entrance of the vertical feed portion contacts the first belt pulley 63 via the carriage belt 65. The sheet feed auxiliary section is composed of the first belt pulley 63, the second belt pulley 64, and the carriage belt 65. The carriage belt 65 rotates to feed the sheet by a driving motor 67, functioning as a driving unit, via the first belt pulley 63.

The carriage belt 65 and the upper surface 17 a of the sheet guiding member 17 define the curve at the feed turning portion. A vertical surface 17 c of the sheet guiding member 17 and a vertical feed guiding plate 66 define the vertical feed portion. A portion contacting the sheet extends beyond the carriage belt 65 over the upper surface 17 a to the feed turning portion. Namely, the carriage belt 65 extends at a position of the upper surface 17 a crossing between a nipping position by the carriage belt 65 and the grip driven roller 55 b and a position where at an edge of the sheet P contacts the vertical surface 17 c of the sheet guiding member 17 or the vertical feed guiding plate 6.

The sheet P is fed by the carriage belt 65, especially by a portion of the belt near the second belt pulley 64, contacting not the upper surface 17 a of the sheet guiding member 17 but the carriage belt 65. When fed by the feed roller 52 and the carriage belt 65, the sheet is moved to the nipping position between the carriage belt 65 and the grip driven roller 55 b at the edge thereof. The firm the sheet P is, the larger pressure is generated between the sheet P and the carriage belt 65, so that the carriage belt 65 feed the sheet P more effectively.

The second belt pulley 64 can be fixed at the position shown in FIG. 10A, or can be retractable by adding an elastic member 68 shown in FIG. 10C which is like a spiral spring or a plate spring. In the latter configuration, the second belt pulley 64 is retracted in “A” direction, when a contacting pressure at a predefined value or higher is applied to the second belt pulley 64 (see FIG. 10C). More particularly, a plurality of the first belt pulleys 63 arranged across the width of the sheet is fixed to one shaft, each opposing to the grip driven roller 55 b. A plurality of the grip driven rollers 55 b is arranged to another shaft. The elastic member 68 applies a pressure so as to keep a predefined nipping pressure between the grip driven roller 55 b and the first belt pulley 63 (see FIG. 10C).

The driving force from the driving unit (the driving motor 67) is delivered to the first belt pulley 63 via the shaft. In association with the first belt pulley 63 rotating in a direction of an arrow, the grip driven roller 55 b rotates in a direction of another arrow. Like the first belt pulley 63, a plurality of the second belt pulleys 64 arranged across the width of the sheet is rotatably attached to another shaft. The elastic member 68 applies pressure on the shaft in a direction opposite to the “All direction (retracting direction). Therefore, in association with rotating of the first belt pulley 63, the second belt pulley 64 linked to the first belt pulley 63 via the carriage belt 65 also rotates in a direction of an arrow. Also, the sheet feed auxiliary section is swingable, in other words can be projected or retracted from the upper surface 17 a of the sheet guiding member 17.

FIG. 11 is a perspective view for explaining the situation in which the sheet-feeding auxiliary device is mounted on the image forming device 100. The sheet auxiliary device also functions as a first feed unit (carriage roller) in the vertical feed portion. The sheet-feeding auxiliary device is depicted in a simplified form omitting the vertical feed guiding plate 66 and the grip driven roller 55 b shown in FIGS. 10A, 10B, and 10C. Of the tree units of the sheet-feeding auxiliary devices, only surfaces of the carriage belts 65 near the first belt pulleys 63 are visible. Although the three units of the sheet-feeding auxiliary devices are arranged across the width of the sheet, the number of units, including one, can be changed as desired, depending on an entire configuration of the image forming device 100.

As described above, in the sheet-feeding auxiliary device of the image forming device 100 according to the fifth embodiment, the sheet feed auxiliary section made up of two pulleys and the carriage belt is provided and positioned opposite to the grip driven roller 55 b located at the entrance of the vertical feed portion, in which the pulley keeps the predefined nipping pressure between the grip driven roller 55 b and the motor drives the pulley and the grip driven roller 55 b. This configuration ensures sheet feed without fail in a small space and minimizes damages on the sheet.

A sheet-feeding auxiliary device of an image forming device 100 according to a sixth embodiment of the present invention is described in details bellow. The image forming device 100 is similar to that according to the first embodiment. Therefore, the identical components are denoted with the same reference numerals and the descriptions of the components are omitted. The sheet-feeding auxiliary device is similar to that according to the first embodiment excepting that the sheet feed auxiliary section including two pulleys and the carriage belt is provided in addition to the grip driving roller 55 a opposed to the grip driven roller of the sheet-feeding auxiliary device, unlike the fifth embodiment in which the sheet feed auxiliary section is provided at a position opposite to the grip driven roller of the sheet-feeding auxiliary device. The overlapped descriptions are omitted and only different portions are described below.

According to the fifth embodiment, the sheet feed auxiliary section is made up of the first belt pulley 63, the second belt pulley 64, and the carriage belt 65, and the first belt pulley 63 or a part of the carriage belt 65 functions as a first feed unit in the vertical feed portion. According to the sixth embodiment, as can be seen from FIG. 12A, the sheet feed auxiliary section is composed of the first belt pulley 63 with a small diameter, the second belt pulley 64, and the carriage belt 65 to be made compact, and in addition, the grip driving roller 55 a is provided at each of the grip driven rollers 55 b so as to make a pair of the grip rollers. FIG. 12A is an enlarged side view of a the sheet-feeding auxiliary device according to the sixth embodiment; FIG. 12B is an enlarged side view for explaining when the belt pulley in FIG. 12A is retracting; and FIG. 12C is a perspective view for explaining when the sheet-feeding auxiliary device is in a driving state. The identical members are denoted with the same reference numerals, and the descriptions of the identical members are omitted.

The second belt pulley 64 can be fixed at a position shown in FIG. 12A, or can be retractable by adding the elastic member 68 (see FIG. 12C) which is like a spiral spring or a plate spring. In the latter configuration, the second belt pulley 64 is retracted in “A” direction, when a contacting pressure at a predefined value or higher is applied to the second belt pulley 64 (see FIG. 12B). More particularly, a plurality of the grip driving rollers 55 a arranged across the width of the sheet is fixed to one shaft, each opposing to the grip driven roller 55 b. A plurality of the grip driven rollers 55 b is arranged to another shaft. An elastic member (not shown) applies a pressure so as to keep a predefined nipping pressure between the grip driven roller 55 b and the grip driving roller 55 a. The driving force from the driving motor 67 is delivered to the grip driving roller 55 a via the shaft. In association with the grip driving roller 55 a rotating in a direction of an arrow, the grip driven roller 55 b rotates in a direction of another arrow.

A plurality of the first belt pulleys 63 arranged across the width of the sheet is rotatably attached to a shaft, and also a plurality of the second belt pulleys 64 are rotatably attached to another shaft. The shaft of the first belt pulley 63 is rotated in a direction of an arrow receiving the driving force from the driving motor 67 via a plurality of gears. The shaft of the second pulley 64 applies a pressure by the elastic member 68 to a direction reverse to the “A” direction (retracting direction). Therefore, in association with rotating of the first belt pulley 63, the second belt pulley 64 linked to the first belt pulley 63 via the carriage belt 65 also rotates in a direction of an arrow. Also, the sheet feed auxiliary section is swingable, in other words can be projected or retracted from the upper surface 17 a of the sheet guiding member 17.

As described with reference to FIG. 10B, the second belt pulley 64 projects at the position where the upper surface 17 a crosses the line between a nipping position by the carriage belt 65 and the grip driven roller 55 b and a position where at an edge of the sheet P contacts on the vertical surface 17 c of the sheet guiding member 17 or the vertical feed guiding plate 6. The sheet P is fed by the carriage belt 65, especially by a portion of the belt near the second belt pulley 64 contacting not the upper surface 17 a of the sheet guiding member 17 but the carriage belt 65. Fed by the feed roller 52 and the carriage belt 65, the sheet is moved to the nipping position between the carriage belt 65 and the grip driven roller 55 b at the edge thereof. The firmer the sheet P is, the larger pressure occurs between the sheet P and the carriage belt 65, so that the more effectively the carriage belt 65 feed the sheet P.

FIG. 13 is an enlarged side view of the first belt pulley 63 and the carriage belt 65 attached to the pulley shaft 69 of the sheet-feeding auxiliary device in FIGS. 12A to 12C. The configuration of the carriage belt 65 bridging over the belt pulley 63 fixed to the pulley shaft 69 makes edges of the carriage belt 65 round, so that the edges of the belt does not heart the sheet when the sheet is fed and no marks by the edges of the belt are laid on the sheet. Tapering for the belt thinner as it goes to the outer edge is also as effective as making the edges round.

FIG. 14 is an enlarged side view of another configuration of the first belt pulley 63 and the carriage belt 65 attached to the pulley shaft 69 of the sheet-feeding auxiliary device in FIGS. 12A to 12C. A diameter of the first belt pulley 63 fixed to the pulley shaft 69 is smaller as it goes to the edges thereof in a direction orthogonal to the sheet feed direction, and the diameter is the largest at the center thereof. Because the carriage belt 65 moves along an outline of the first belt pulley 63, the edges of the carriage belt 65 does not heart the sheet when the sheet is fed. This configuration is also effective to protect from creases by the belt. As can be seen from FIG. 15, a standalone roller 71 can be used as the sheet feed auxiliary section. When the firm sheet contacts the roller 71, the roller 71 helps the sheet to be fed. FIG. 15 is a side view for explaining a modification of the sheet feed auxiliary section according to the sixth embodiment in which the roller 71 is replaced with the pulley and the carriage belt. The identical members are denoted with the same reference numerals and the descriptions of the identical members are omitted.

FIG. 16 is a perspective view of a configuration of the carriage belt 65 and related pulleys of the sheet-feeding auxiliary device. The carriage belt 65 bridged over the first belt pulley 63 fixed to the first pulley shaft 69 and the second belt pulley 64 fixed to the second pulley shaft 70 rotates in a direction along the fist belt pulley 63 rotates. In this case, a flat pulley and a flat belt can be used as the first belt pulley 63 and the carriage belt 65 respectively to deliver the driving force with frictional contact therebetween. It is more effective to use a geared pulley and a back face-geared belt as the first belt pulley 63 and the carriage belt 65 respectively to deliver the driving force with engagement of the teeth. When the pulley shafts 69 and 70 can rotate to the feed unit, the belt pulleys 63 and 64 are fixed to the pulley shafts 69 and 70 to rotate as an integrate unit. The surface of the carriage belt 65 is made of ethylene-propylene rubber suitable for feeding. It is more effective to make the entire carriage belt 65 of ethylene-propylene rubber.

FIG. 17 is a perspective view for explaining the situation in which the sheet-feeding auxiliary device is mounted on the image forming device 100. Three grip driving rollers 55 a are provided in the vertical feed portion, and two sheet-feeding auxiliary devices are located between the grip driving rollers 55 a. At the entrance of the vertical feed portion, the sheet is fed mainly by the grip driving rollers 55 a and secondary also by the carriage belt 65. In the example, each of the two driving rollers 55 is located between the three grip driving rollers 55 a. When there are only two carriage belts 65, it is recommended to arrange the two carriage belts 65, for example, at both ends across the width of the sheet.

As described above, in the sheet-feeding auxiliary device of the image forming device 100 according to the sixth embodiment, the sheet feed auxiliary section made up of two pulleys and a carriage belt is provided upstream of the grip driving roller 55 a positioned at the entrance of the vertical feed portion, and the elastic member 68 applies a pressure on the lower pulley (the second belt pulley 64) toward the sheet guiding member 17 opposed to the second belt pulley 64. This configuration ensures sheet feed without fail in a small space and minimizes damages on the sheet.

It is allowable to modify the number of the carriage belt 65, the diameter of pulleys 63 or 64 over which the carriage belt 65 is bridged, and the driving system for the carriage belt 65 according to the necessity. The material for the carriage belt 65 described above is an example, and another material can be used if suitable. Furthermore, another separating process can also be employed for the separating section other than the FRR. According to the sixth embodiment, the three carriage belts 65 are arranged across the width of the sheet, one at the center and the other two at positions away from the center by an equal space. Any arrangement is allowable, and only one carriage belt 65 can be positioned at the center. Although the carriage belts 65 are arranged across the width of the sheet with intervals, it is possible to use a belt which stretches across the entire width of the sheet.

The image forming process by the image forming device 100 can be modified as desired. In the embodiments, the image forming device 100 employs the intermediate transfer method, and the configuration and operation of the method is as described with reference to FIG. 1. However, the image forming device 100 can employ the direct transfer method shown in FIG. 18. FIG. 18 is a side view for explaining an overview of a modified configuration of the image forming device 100 employing a direct transfer method according to any of embodiments. Like in FIG. 2, the sheet path for single-side printing is shown with a solid line (6).

The image forming device 100 can employ an ink-jet method. The sheet-feeding auxiliary device can be used at a position for changing a feed direction in a device having the sheet feed function such as a scanner or an ADF in addition to the image forming device.

The sheet-feeding auxiliary device according to any of the first to sixth embodiments can be mounted at various suitable positions in the image forming device such as a position for turning feed direction after the toner image is fixed, a position for turning feed direction to eject the sheet, and a position for turning the feed direction to feed the sheet into the duplex unit 60, in addition to the position right after the separating section.

An exemplary modification in which the sheet-feeding auxiliary device is used in a scanner with an ADF is described below. FIG. 19 is a longitudinal side view of a scanner 200 for explaining an outline of an internal configuration thereof. The scanner 200 includes a scanner body 202 and a reversing automatic document feeder (RADF) 203, a kind of ADF, provided at an upper portion of the scanner body 202.

There are provided at an upper face of a housing 204 of the scanner body 202 a document glass plate 205 on which a book-shaped document is placed for scanning performed on a book-shaped document scanning mode and a document glass plate for ADF 206 though which a sheet-type document is scanned on a sheet-type document scanning mode.

The book-shaped document scanning mode is one of operational modes for scanning the document placed on the document glass plate 205, and the sheet-type document scanning mode is another operational mode for scanning the document automatically fed to pass through the document glass plate for ADF 206. A user can set the operational mode with an operational panel (not shown) provided outside of the housing 204.

The RADF 203 used on the sheet-type document scanning mode is described below. When the sheet-type document scanning mode is ON, a first carriage 210 (not shown) and a second carriage 213 (not shown) are stopped at home positions under the document glass plate for ADF 206, and the RADF 203 scans the automatically fed document.

The RADF 203 includes a document tray 220 for setting a document 250 to be scanned on the sheet-type document scanning mode, an ejecting section 221 for ejecting the scanned document 250, and a path 222 communicating from the document tray 220 to the ejecting section 221, and a reversing section 223 for reversing the document 250 when a duplex scanning mode is set. The duplex scanning mode is one of the sheet-type document scanning mode, in which the document 250 is reversed, after automatically fed by the RADF 203 and scanned on a top face thereof, to be scanned the back face thereof.

In the path on a side of the document tray, there are located a pick-up roller 231 for feeding the documents 250 on the document tray one by one and a carriage roller 232. The pick-up roller 231 and the carriage roller 232 are driven by a feed motor (not shown). The documents 250 placed on the document tray 220 are fed one by one into the path 222 with the pick-up roller 231 and the carriage roller 232 rotated by the feed motor. Provided in the path is a carriage drum 233 for feeding the document 250 to the ejecting section 221. The document glass plate for ADF 206 is located under the carriage drum 233. The carriage drum 233 is driven by a stepping motor (not shown). It means that the document 250 is introduced, after fed from the document tray 220 into the path 222, onto the document glass plate for ADF 206 by the carriage drum 233 rotated by the stepping motor.

The documents 250 placed on the document tray 220 are fed by the pick-up roller 231 one by one and carried to the document glass plate for 206 or a scanning position by the carriage drum 233.

The reversing section 223 includes a reversing table 236 for defining a reverse path 235 communicating to a bifurcation 234 positioned at a middle of the path 222. The reversing table 236 is provided with a reverse roller 237 rotatable in both directions driven by a feed and reverse motor (not shown). The reversion path 235 is provided with a bifurcating claw 238 pivotable on a spindle. The bifurcating claw 238 sorts the document 250 fed from the carriage drum 233 to an ejecting unit 270 into two paths, one for the reversing section 223 and the other for the ejecting section 221 by switching connection to the path 222 with pivot. When the duplex scanning mode is ON, the bifurcating claw 238 connects the reversion path 235 to the path 222 to introduce the document 250 carried by the carriage drum 233 into the reverse path 235, and then the reversed document 250 is carried into the path 222 again by the reverse roller 237.

The sheet-feeding auxiliary device can be used in the scanner 200 according to the exemplary modification at a curve A, which is positioned between the scanning position and the ejecting unit 270, or the reversing section 223.

The turn roller 54 or the first belt pulley 63 and the second belt pulley 64 over which the carriage belt 65 is bridged can be provided at the curve A where the feed direction is steeply turned between the carriage drum 233 and the ejecting unit 270 in the path and the curve B between the reversing section 223 and the carriage drum 233. The turn roller 54 or the first belt pulley 63 and the second belt pulley 64 over which the carriage belt 65 is bridged can be provided at any curves of any portions in the path where the feed direction is steeply changed.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth. 

1. A sheet-feeding auxiliary device comprising: a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.
 2. The sheet-feeding auxiliary device according to claim 1, further comprising: a non-driven auxiliary rotating member provided in parallel to the rotating member.
 3. The sheet-feeding auxiliary device according to claim 1, wherein the driving unit drives the rotating member at a speed identical to a speed of feeding the sheet.
 4. The sheet-feeding auxiliary device according to claim 1, wherein a distance between outside edges of the rotating member in an axial direction is 90 millimeters.
 5. The sheet-feeding auxiliary device according to claim 1, further comprising: a roller member provided on a side of a downstream of the rotating member in the sheet path, wherein the driving unit drives or stops the rotating member in sync with the roller.
 6. The sheet-feeding auxiliary device according to claim 5, wherein the driving unit drives the rotating member via the roller by driving the roller member.
 7. The sheet-feeding auxiliary device according to claim 1, further comprising: a feed roller provided on a side of an upstream of the rotating member in the sheet path, the feed roller being driven in conjunction with the rotating member; and a one-way clutch that is engaged with the rotating member, wherein the rotating member rotates in a driving direction when a force that rotates the rotating member in a same direction as the driving direction is received from outside.
 8. The sheet-feeding auxiliary device according to claim 1, wherein the rotating member includes at least two pulleys with a belt bridged, and a surface of the belt opposed to the sheet guiding member supports the sheet path from an inner circumferential side.
 9. The sheet-feeding auxiliary device according to claim 8, wherein one of the pulleys provided on a side of a downstream in the sheet path functions as one of a pair of first carriage rollers.
 10. The sheet-feeding auxiliary device according to claim 8, further comprising: an elastic member that applies a pressure on one of the pulleys provided on a side of an upstream in the sheet path, wherein the pulley provided on the side of the upstream in the path can be retracted from the sheet path against the elastic member.
 11. The sheet-feeding auxiliary device according to claim 8, wherein the driving unit rotates one of the pulleys provided on a side of a downstream in the sheet path.
 12. The sheet-feeding auxiliary device according to claim 1, wherein a plurality of the rotating members is provided across a width of the sheet.
 13. The sheet-feeding auxiliary device according to claim 1, further comprising: a pair of rollers that holds the sheet to feed the sheet to a downstream of the sheet guiding member in the sheet path, wherein the rotating member assists the pair of rollers to feed the sheet.
 14. An image forming device comprising: a sheet-feeding auxiliary device that is arranged at an inner circumferential side of a sheet path, the sheet-feeding auxiliary device including a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.
 15. The image forming device according to claim 14, wherein the sheet-feeding auxiliary device is provided in either one of a first path leading to a reversing unit that reverses one surface and other surface of the sheet and a second path extending from the reversing unit, in the sheet path.
 16. An image reading device comprising: a document tray on which a sheet of a document is placed; a document feeding unit that feeds the sheet of the document into a sheet path; a reading unit that reads the sheet of the document fed in the sheet path, as an image; a reversing unit that reverses one surface and other surface of the sheet of the document fed in the sheet path; a sheet guiding member that is provided outside of a feed turning portion for changing a direction of feeding a sheet in a sheet path; a rotating member that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving unit that drives the rotating member.
 17. A sheet-feeding auxiliary device comprising: a sheet guiding means for changing a direction of feeding a sheet in a sheet path member, the sheet guiding means being provided outside of a feed turning portion; a rotating means that is provided inside of the feed turning portion in opposite to the sheet guiding member; and a driving means for driving the rotating member. 